SpaceX is now hoping to launch "Zuma" into orbit via one of the company's Falcon 9 rockets on Sunday after nearly two months of delays. What exactly Zuma is, though, is still a big secret.

Northrop Grumman confirmed to me in November that it had contracted with Elon Musk's commercial space venture to do the launch on behalf of a US government agency, which it didn't name. It provided no other details about the payload.

After an original mid-November target, SpaceX set Friday evening as its targeted launch date for Zuma from Florida. But weather conditions have pushed the launch back by two days, SpaceX said Thursday evening.

Team at the Cape completed additional propellant loading tests today. Extreme weather slowed operations but Falcon 9 and the Zuma spacecraft are healthy and go for launch—now targeting January 7 from Pad 40 in Florida.